Had a scary experience today.  I flew out about 2500ft and took some pictures.  I initiated RTH and while having a conversation with someone and listening to the beeping sound of the RTH, I patiently waited.  At approximately 800 feet from me, I looked up and saw my bird coming.  Then suddenly and stopped like it had sensed an object.  After that it started drifting our of control.  First, I'm glad I had my eyes up and looking at it because I wouldn't have see that happen had I continued talking.  I immediately took control but it was difficult to control.  After a terrifying ordeal, I had it come back overhead and landed.  
The landing was not the usual soft landind.
When I examined the bird, I immediately noticed that the battery had swolen and had actually cracked in mid-flight. I never thought this were possible.

Hi refalsi, thank you for reaching DJI Forum. I'm sorry to know about the issue you've encountered with your drone. Please be advised that if an incident occurred and the unit encountered a crash or hard landing, we would suggest for the unit to be sent in for a proper diagnosis and repair. If your drone is within the warranty period we suggest contacting our relevant team for further assistance on the request through this link: https://www.dji.com/support We will send you an offer based on the results. You may kindly check the warranty period through this link: https://www.dji.com/service/policy, thank you.

You were lucky. Usually when the batteries swell they pop out causing the drone to fall from the sky.   Sadly you'll need another battery as thats not safe to fly.

Definitely a scary event that could have ended up much worse.  Unfortunately, that battery is toast.  Time for a replacement battery.  

DAFlys Posted at 7-29 03:19
You were lucky. Usually when the batteries swell they pop out causing the drone to fall from the sky.   Sadly you'll need another battery as thats not safe to fly.

WOW...didn't think that were possible.  I was certainly lucky then.  My 2nd battery is about the same age as the one that failed and I'm thinking I'll just replace both, rather than hoping the 2nd one doesn't fail the same way.

DowntownRDB Posted at 7-29 17:25
Definitely a scary event that could have ended up much worse.  Unfortunately, that battery is toast.  Time for a replacement battery.

Yup.  New batteries on the way.  Thanks

refalsi Posted at 7-30 18:08
Yup.  New batteries on the way.  Thanks

Glad to hear you have a new one on the way.  Better to be safe.